department of environmental protection...table c-1 lists the effluent limit guidelines from 40 cfr...
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563-2112-115 / DRAFT December 27, 2014 / Page i
DEPARTMENT OF ENVIRONMENTAL PROTECTION
Bureau of Mining Programs
DOCUMENT NUMBER: 563-2112-115
TITLE: Developing National Pollutant Discharge Elimination System (NPDES)
Permits for Mining Activities
EFFECTIVE DATE: Upon publication of notice as final in the Pennsylvania Bulletin.
AUTHORITY: Surface Mining Conservation and Reclamation Act, Coal Refuse Disposal
Control Act, Non-Coal Surface Mining Conservation and Reclamation
Act, and The Clean Streams Law.
POLICY: DEP will implement the requirements of the Laws and Regulations for
issuing NPDES permits associated with mining activities.
PURPOSE: The purpose of this guidance is to provide direction establishing effluent
limits for NPDES permits associated with mining activities to ensure
timely and compliant point source permitting.
APPLICABILITY: This guidance applies to NPDES permits associated with mining activities.
DISCLAIMER: The policies and procedures outlined in this guidance are intended to
supplement existing requirements. Nothing in the policies or procedures
shall affect regulatory requirements.
The policies and procedures herein are not an adjudication or a regulation.
There is no intent on the part of DEP to give the rules in these policies that
weight or deference. This document establishes the framework within
which DEP will exercise its administrative discretion in the future. DEP
reserves the discretion to deviate from this policy statement if
circumstances warrant.
PAGE LENGTH: 23 pages
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Procedures for Developing NPDES
Requirements for Mining Activities
REGULATORY FRAMEWORK
NPDES permitting for mine sites is done in the context of the following regulations:
Chapter 77 Noncoal Mining
Chapter 86 Surface and Underground Coal Mining: General
Chapter 87 Surface Mining of Coal
Chapter 88 Anthracite Coal
Chapter 89 Underground Mining of Coal and Coal Preparation Facilities
Chapter 90 Coal Refuse Disposal
Chapter 92a *NPDES Permitting, Monitoring and Compliance
Chapter 93 Water Quality Standards
Chapter 95 Wastewater Treatment Requirements
Chapter 96 Water Quality Standards Implementation
*Chapter 92a incorporates significant sections of the federal regulations at 40 Code of Federal
Regulations (CFR). Cross-references to federal regulation citations are included to provide a complete
regulatory roadmap.
NPDES permitting for mining under Chapter 92a is coordinated with the permitting of the mining
activity under Chapters 77, 86, 87, 88, 89 and 90. The NPDES permit and the mining activity permit are
interdependent and are reviewed and processed together.
BACKGROUND
NPDES permits must ensure compliance with all applicable water quality standards which include
existing and designated surface water uses, narrative and numeric water quality criteria, and the
antidegradation program (see TGD 391-0300-002).
Water Quality Criteria
NPDES permits are to be issued to comply with both numeric and narrative water quality criteria,
designed to protect receiving stream uses and quality. Effluent limits established to comply with water
quality criteria are referred to as water quality based effluent limits (WQBELs).
Narrative Criteria
The general narrative water quality criterion is stated in the regulations at Chapter 93, § 93.6(a), “Water
may not contain substances attributable to point or nonpoint source discharges in concentration or
amounts sufficient to be inimical or harmful to the water uses to be protected or to human, animal, plant
or aquatic life.” This criterion is applicable to designated and existing uses.
In addition, the water quality criteria at Chapter 93, § 93.6(b) address “floating materials, oil, grease,
scum and substances which produce color, tastes odors, turbidity or settle to form deposits.”
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Mining permit applications must be reviewed with respect to the narrative criteria to protect the water
quality, particularly for two specific uses, as a public water supply (PWS) and for aquatic life. With
respect to sulfate, total dissolved solids (TDS) and specific conductance (SC), the PWS use protection is
implemented at the point of intake from a stream for the PWS, with a numeric limit at the intake point of
500 mg/l TDS (and 250 mg/l Sulfate). (Table 3 in § 93.7 includes numeric water quality criteria.) The
aquatic life narrative criterion is implemented by Osmotic Pressure (OP) (the numeric in-stream limit is
expressed as a maximum of 50 mOsm/kg) and evaluation for other toxic substances. The OP criterion is
intended to protect aquatic life with respect to the effects of TDS/Sulfate/SC. Use of this water quality
criterion is the most effective way to assure protection of aquatic life since there are currently no
numeric water quality criteria promulgated for TDS or sulfate relating to aquatic life.
Numeric Criteria
Numeric water quality criteria are expressed in a variety of ways. For example, the criteria for the
metals of primary concern for coal mining (iron, manganese and aluminum) each are expressed
differently. The criterion for manganese is expressed as a maximum (1.0 mg/l, PWS). The criterion for
iron is expressed as a 30-day average (1.5 mg/l-total, fisheries) and maximum (0.3 mg/l-dissolved,
PWS). The criterion for aluminum is expressed as a Criteria Maximum Concentration (CMC)
(750 ug/l). As a result, translating the criteria to limits is different for each metal.
The PWS criteria for sulfate, TDS and chloride must be met at the point of existing or planned surface
water supply withdrawals. (Chapter 96, § 96.3(d))
Where limits are required for the 30-day average, daily maximum and instantaneous maximum, the ratio
of the limits is 1:2:2.5, where the daily maximum is two times the 30-day average and the instantaneous
maximum is 2.5 times the 30-day average.
Technology-Based Effluent Requirements
Appendix C of this guidance summarizes the technology based effluent requirements for mining.
Table C-1 lists the effluent limit guidelines from 40 CFR 436 for noncoal mining. Pennsylvania‟s
regulations at Chapter 77, § 77.522 list limitations for pH and “other parameters the Department may
require.”
Table C-2 in Appendix C describes the technology-based effluent requirements for coal mining
activities. These limits are categorized by the source of the water (i.e. pit water or runoff) and the
precipitation conditions. These limits are based on the framework in 40 CFR 434.
DEP incorporates the more stringent of these limitations or any limits required to implement the state
water quality criteria in the NPDES permits.
APPLICATION AND REVIEW PROCESS
The steps for the review of NPDES applications for mine sites include:
1. Application Received - notice in Pennsylvania Bulletin
2. Review Effluent Characterization information
3. Conduct Reasonable Potential Analysis
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4. Calculate effluent limits
5. Prepare Draft Permit and Fact Sheet
6. Publish notice of Draft Permit in Pennsylvania Bulletin
7. Send required information to the U.S. Environmental Protection Agency (EPA) for review and
comment/objection for NPDES permits related to a total maximizer daily load (TMDL) and in
the Monongahela watershed
8. Review comments/objections
9. Public hearing (if requested and there is significant public interest)
10. Prepare final permit documents (and written findings)
11. Issue/Deny Permit
12. Notice of action in Pennsylvania Bulletin
13. Effluent Characterization Results submitted by applicant within two years of discharge
14. DEP evaluates Effluent Characterization data to determine if permit modifications are needed
Effluent Characterization
The regulations at Chapter 92a, § 92a.21 which incorporates 40 CFR 122.21 (wastewater) and
Chapter 92a, § 92a.32 which incorporates 40 CFR 122.26 (stormwater) require that an applicant submit
an effluent characterization (i.e. identifying what pollutants are expected to be discharged) as part of the
permit application. The Application for Individual NPDES Permit Associated with Mining Activities
(5600-PM-BMP0032) includes effluent characterization requirements in section D. The goal of effluent
characterization is to assure that the nature and quantity of pollutants in the effluent, as well as their
effect on the receiving waters, is fully evaluated during the application review and permit development
process.
Resources are available to assist an applicant determine if a pollutant should be expected to be present in
the effluent and to assist DEP in reviewing this information. These resources include the Development
Document for Effluent Limitations Guidelines and Standards for the Coal Mining Point Source Category
(US EPA, 1982), data from adjacent or similar sites, datasets collected by the U.S. Geological Survey
(USGS) as part of a survey of coal mine discharge characteristics in Pennsylvania, data collected and
presented by the PA Coal Association and the PA Aggregates and Concrete Association.
The pollutants for which sampling may be required are listed in various categories in Appendix D of
40 CFR 122. They are organized in tables:
Table II Organic Toxic Pollutants
Table III Other Toxic Pollutants (Metals and Cyanide) and Phenols
Table IV Conventional and Nonconventional Pollutants
Table V Toxic Pollutants and Hazardous Substances
In addition, there are effluent characterization requirements that are cited elsewhere in the regulations
(i.e. not in tables).
The effluent characterization requirements are summarized in Appendix A.
The regulations at 40 CFR 122.21(g)(7)(ii) state that “an applicant is expected to „know or have reason
to believe‟ that a pollutant is present in an effluent based on an evaluation of the expected use,
production, or storage of the pollutant, or on any previous analyses for the pollutant.”
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On sites with multiple outfalls, with substantially identical effluents, DEP may allow the applicant to
test only one outfall for effluent characterization purposes and report that outfall as representative of the
substantially identical outfall. (40 CFR 122.21(g)(7)(i))
Under Section 402(k) of the Clean Water Act, 42 U.S.C § 1342(k), an NPDES permit provides
authorization and a shield for the discharge of the following pollutants resulting from facility processes,
waste streams and operations that have been clearly identified in the permit application process when
discharged from specified outfalls: (1) pollutants specifically limited in the permit or pollutants which
the permit, fact sheet or administrative record explicitly identify as controlled through indicator
parameters; (2) pollutants for which the permit authority has not established limits or other permit
conditions, but which are specifically identified in writing as present in facility discharges during the
permit application process and contained in the administrative record which is available to the public;
and pollutants not identified as present but for which constituents or waste streams, operations or
processes were clearly identified in writing during the permit application process and contained in the
administrative record which is available to the public.
Generally, an applicant must provide a narrative description that includes the significant materials used
or stored on-site in the previous three years and the manner and frequency that pesticides, herbicides,
soil conditioners and fertilizers are applied. Significant materials is a defined term that includes raw
materials, fuels, solvents, detergents, hazardous substances, fertilizers, pesticides and waste products
(e.g. ash, slag or sludge). (40 CFR 122.26(b)(12)) Those significant materials that were treated, stored
or disposed of in a manner that would allow exposure to stormwater and therefore have the potential to
be released in a stormwater discharge must be reported. (40 CFR 122.26(c)(i)(B)) For mine sites where
coal ash is beneficially used for reclamation, the required coal ash water monitoring data may be used to
supplement the effluent characterization data.
Two-year Sampling Requirement: Within the first two years of the initial discharge from an outfall,
some effluent characterization analysis is required in order to confirm the presence and concentration of
those parameters designated as believed to be present. 40 CFR 122.21(k)(5)(vi) requires sampling
within two years of the initiation of a treatment pond discharge. 40 CFR 122.26(c)(1)(i)(G) requires
new stormwater sources to provide data within two years after the commencement of discharge. These
requirements are summarized in Appendix A. A form is available to report the required effluent
characterization data. DEP evaluates the data for presence or absence of the pollutants. For those
parameters present, follow up sampling may be required. The follow-up sample results are then
evaluated based on the criterion maximum concentration water quality criteria in Table 5 of
Section 93.8. The Table 5 limits for toxic metals are expressed as dissolved metals and many of the
toxicity levels are related to hardness, so follow-up samples for metals need to be filtered and include
hardness. Discharges exceeding the Table 5 limits are evaluated for effluent limits for any parameter
which exceeds or has the potential to exceed water quality criteria.
Stormwater Requirements: Stormwater includes the discharge of surface runoff, snow melt runoff and
drainage from any conveyance used for collecting and conveying the runoff water that is directly related
to manufacturing, processing or raw material storage areas, including the overburden and mineral being
mined. (40 CFR 122.26(b)(14)) An applicant for a new NPDES permit for stormwater related to a mine
needs to include a description of the significant materials used at the site within the past three years and
the herbicides, pesticides and fertilizers used at the site. An applicant for a new mine discharge needs to
provide estimates (and the source of the estimates) for the stormwater facilities for total suspended
solids, pH, acidity/alkalinity, Oil and Grease, Biological Oxygen Demand (BOD), Chemical Oxygen
Demand (COD), phosphorus, Kjeldahl nitrogen, Nitrite/Nitrate nitrogen, flow and any other items they
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would expect from Table IV (e.g. sulfate, aluminum and magnesium for coal mines). Coal mines must
also report iron and manganese since these pollutants are limited by effluent limit guidelines. (40 CFR
122.26(c)(i)(E))
The review of the effluent characterization data results in a reasonable potential analysis for pollutants
that are present in concentrations at or above the water quality criterion for that pollutant.
Reasonable Potential Analysis
A reasonable potential analysis is used to determine if a discharge could lead to a violation of the water
quality standards. The regulations at Chapter 92a, § 92a.44 incorporate 40 CFR 122.44. The context of
reasonable potential analysis is established in the following sections:
Limitations must control all pollutants or pollutant parameters which may be discharged at a
level which will cause, have the reasonable potential to cause, or contribute to an excursion
above any State water quality standard, including State narrative criteria for water quality.
(40 CFR 122.44(d)(1)(i))
When determining whether a discharge causes, has the reasonable potential to cause, or
contributes to an in-stream excursion above a narrative or numeric criteria within a State water
quality standard, the permitting authority shall use procedures which account for existing
controls on point and nonpoint sources of pollution, the variability of the pollutant or pollutant
parameter in the effluent, the sensitivity of the species to toxicity testing (when evaluating whole
effluent toxicity), and where appropriate, the dilution of the effluent in the receiving water.
(40 CFR 122.44(d)(1)(ii))
When the permitting authority determines, using the procedures in paragraph (d)(1)(ii) of this
section, that a discharge causes, has the reasonable potential to cause, or contributes to an in-
stream excursion above the allowable ambient concentration of a State numeric criteria within a
State water quality standard for an individual pollutant, the permit must contain effluent limits
for that pollutant. (40 CFR 122.44(d)(1)(iii))
When the permitting authority determines, using the procedures in paragraph (d)(1)(ii) of this
section, that a discharge causes, has the reasonable potential to cause, or contributes to an in-
stream excursion above the numeric criteria for whole effluent toxicity, the permit must contain
effluent limits for whole effluent toxicity. (40 CFR 122.44(d)(1)(iv))
Reasonable potential analysis is completed for pollutants of concern. Pollutants of concern include
parameters which have regulatory effluent limitations, those that are identified through effluent
characterization and those for which there is a listed or actual impairment in the receiving stream.
TMDL Streams: Where there is a final TMDL, reasonable potential analysis includes the review of the
TMDL report. WQBELs are developed based on the TMDL report. TMDL reports may be revised to
accommodate a new permit or to adjust a waste load allocation for an existing facility that may not have
been addressed in the report. When reviewing TMDL requirements, consideration may be required of
downstream TMDLs. Where TMDLs are written for a larger water body, a WQBEL may be needed for
the immediate receiving stream.
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Limits established to comply with the TMDL are WQBELs. The most stringent limits from all the
evaluations are to be applied to protect all uses. The review of an NPDES application includes the
evaluation of water quality criteria for all pollutants that are expected to be present. If a facility is in a
watershed with a TMDL but does not have waste load allocation (WLA) for the pollutants of concern,
there may or may not be reasonable potential to cause or contribute to an excursion above applicable
water quality criteria. A reasonable potential analysis for those facilities should be conducted. Based on
the types of activities and minimal flow of the discharges, some permits may be considered negligible
discharge facilities (in that they typically discharge with pollutant levels below water quality criteria),
and the permit reviewer might determine that the pollutant contributions of metals from these permitted
sources are negligible. Under these conditions, these minor discharges are authorized to operate under
their current levels. For TMDL streams, it may be determined that some facilities have the reasonable
potential to cause or contribute to an impairment but those facilities do not have a WLA in a TMDL. In
that case, setting effluent limits at the numeric criteria prevents the discharge from causing or
contributing to a violation of the criteria. TMDLs have not typically been done for TDS related
pollutants in Pennsylvania. The future growth section of the TMDL report typically lists the options for
approving new outfalls.
Many of the acid mine drainage (AMD) TMDLs developed by Pennsylvania and approved by EPA do
not specifically account for the discharges from stormwater controls in mining permits. This is because
the effects from sedimentation ponds are considered negligible since the potential discharges from the
ponds are based on infrequent events and the ponds should rarely discharge if reclamation and
revegetation is concurrent. All stormwater ponds are designed in accordance with 25 Pa.
Code 87.108(h) to contain, at a minimum, runoff from a 10-year, 24-hour precipitation event. If a
waterbody was identified as impaired for sediment the TMDL may include sediment WLAs.
Stormwater discharges are specifically considered in those TMDLs and sediment WQBELs should be
included based upon the sediment WLAs.
For the Kiski-Conemaugh TMDL, a dynamic model was used and stormwater facilities are specifically
accounted for within it. Any parameter for which there is a TMDL is not eligible for alternate
precipitation provisions of 25 Pa. Code §§ 87.102, 88.92, 88.187, 88.292, 89.52 and 90.102. For
example, if a limit for manganese is based on a WLA, the limit associated with the WLA (this could be
best available technology (BAT)) applies at all times. Because of the relationship between iron and
TSS, in the Kiski-Conemaugh TMDL iron WLAs are also provided for facilities with stormwater
discharges that are regulated under NPDES permits that contain iron or total suspended solids (TSS)
limitations.
If there is no assimilative capacity in the receiving stream (i.e. the Q7-10 flow is zero or the ambient
stream water quality exceeds a numeric criterion), then there may be a reasonable potential for a
discharge to cause or contribute to a violation of a water quality criterion. Setting effluent limits at the
numeric water quality criterion or using non-discharge alternatives in cases where there is no
assimilative capacity prevents the discharge from causing or contributing to a violation of the criteria.
Background Data Review for Assessing Reasonable Potential: There are various ways to determine if
there is a reasonable potential for a discharge to cause or contribute to a violation of the in-stream limits.
If any of these approaches conclude that there is a reasonable potential, the permit is to include
appropriate water quality based effluent limits. Data from statewide sampling over the last several years
indicates, generally, that surface mining in Pennsylvania does not have a reasonable potential to produce
high TDS waters that would have an impact on aquatic life. However, this needs to be documented on a
site-specific basis for each permit application.
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Mass balance calculations for sulfate and TDS should be completed for the closest downstream PWS
intake using Q7-10 flow and ambient quality (or the numeric criterion) for the intake and average
expected discharge flow and concentration. If the calculated change is not measurable at the intake or
there is assimilative capacity, then there is no reasonable potential for the discharge to cause or
contribute to a violation of the PWS water quality standard. For the purposes of this PWS evaluation
when the in-stream values are near the water quality criterion, laboratory analysis variability is used to
determine if the difference will be measurable. Chapter 5 of the guidance document for NPDES
permitting (362-0400-001) includes a table (5-1a) which lists the variability of results for various
analytical methods. This should be used as a reference for determining if a projected change will be
measurable. For example, the variability for the most sensitive analytical method for sulfate is 1.6 mg/l.
Therefore, in evaluating the PWS standard, if the mass balance calculations result in a difference less
than 1.6 mg/l sulfate, there is no reasonable potential for the discharge to cause or contribute to a
violation of the in-stream criteria. Table 5-1a indicates that the variability for TDS is 5.2 mg/l and
1.54 mg/l for chloride.
Overburden Analysis: For a site where the overburden analysis shows overburden with high sulfur and
high neutralization potential, there is the potential to produce TDS. For a site where the overburden
analysis shows overburden with high sulfur and low neutralization potential (and alkaline addition is
proposed), then there is a reasonable potential to produce high TDS water. Setting an instantaneous
maximum limit for these cases for OP at the in-stream water quality criterion (50 mOsm/kg) complies
with 40 CFR 122.44(d)(1)(iii). Note that the regulations at Chapter 95, § 95.10 exclude pre-existing
discharges, pit water discharges from surface mines with a pit area less than 450,000 square feet, and
surface mine erosion and sedimentation control facilities from the treatment requirements under
Chapter 95. However, this exclusion is limited to determining the applicability of Chapter 95.
If a review of data from adjacent mine sites shows that the mining could produce pit water with TDS
greater than 1,500 mg/l, then there may be a reasonable potential to cause an in-stream excursion above
the aquatic life narrative criterion. Also, under Chapter 95, an effluent limit for TDS may be required if
a pit size variance (i.e. the approved area exceeds 450,000 square feet) is approved. In order to protect
the receiving waters with respect to the PWS standard, sulfate and TDS data need to be evaluated to
assure the prevention of a violation at the nearest downstream intake.
As an example, for a surface mine, a reasonable potential analysis would consist of:
Overburden analysis (if applicable)
Water Quality Spreadsheet (WQSS) evaluation
DEP has developed a mass balance based spreadsheet for evaluating the numeric criteria for
metals and acidity for mine sites. This spreadsheet is described in detail in Appendix B. If the
WQSS analysis results in WQBELs which are more stringent than BAT limits, then there is a
reasonable potential. The imposition of the WQBELs based on water quality criteria meets the
requirements of 40 CFR 122.44(d)(1)(iii).
TMDL evaluation
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SETTING EFFLUENT LIMITS
If it is determined that there is a reasonable potential for a violation of water quality standards, then:
WQBELs (when more stringent than BAT) are to be applied
For TDS, an OP limit needs to be imposed as the aquatic life criterion
For the PWS standard, TDS and/or Sulfate limits (depending on assimilative capacity) need to be
imposed
Osmotic Pressure Limits: OP represents the effect of dissolved constituents in the water on aquatic life.
Generally, the higher the concentration of TDS, the higher the OP. If the conclusion of the reasonable
potential analysis is that there is a reasonable potential to exceed the aquatic life criteria relating to TDS,
then an instantaneous maximum limit of 50 mOsm/kg is the default effluent limit for OP. Because
50 mOsm/kg is the in-stream criterion for OP and the OP limit was established to protect aquatic life
from the effects of pollutants, this is a conservative approach to protect aquatic life (i.e. it requires that
the effluent at no time exceed the criterion).
An applicant can request a higher limit. In order for a higher limit to be applied, it needs to be shown
that there is existing assimilative capacity in the receiving stream to accommodate higher concentrations
of dissolved pollutants. The demonstration ought to show that the alternative limit will be protective of
the aquatic life use. This demonstration can be accomplished through a mass balance calculation. It is
not appropriate to do a mass balance calculation with OP data since the units are mOsm/kg, rather than
mg/l, therefore an applicant should provide the data necessary to evaluate a higher OP limit, which
includes OP and TDS background data for the receiving stream below the proposed discharge
location(s).
While laboratory determinations will be needed to calculate an alternative OP effluent limit, estimating
OP levels may be useful in some cases, such as when conducting a reasonable potential analysis using
existing data. The following method may be used to estimate OP. While the estimates described below
are helpful, additional data (TDS and/or OP) should be obtained in cases where the estimates are
insufficient to rely upon (i.e., where the values are near the 50 mOsm/kg criterion).
Site-specific or other relevant data for OP should be used when it is available. However, for the purpose
of estimating OP when data is not available, the following estimation may be used:
OP (mOsm/kg) ~ TDS (mg/l)/34
Similarly, site-specific or other relevant TDS data should be used when it is available. If TDS data is
not available and conductivity data is, the following estimate for TDS may be used:
SC*0.83~TDS
In order to conduct the reasonable potential analysis, the expected quality of the discharges and the
receiving stream quality needs to be evaluated. If the discharge is expected to be high in any pollutant
(including TDS), then limits (including OP, if TDS is the pollutant at issue with respect to the aquatic
life narrative standard) are to be imposed. If the analysis concludes that there is no reasonable potential
for the discharges to cause or contribute to a violation of the water quality (WQ) standards, then the
reason for this needs to be documented in the fact sheet and written findings.
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When specific constituent data is available, it may be useful to estimate OP based on the data. For
estimating OP the following conversions may be used:
Constituent Osmolality (mOsm/kg per mg/l)
Sulfate 0.0104
Chloride 0.0282
Sodium 0.0434
Magnesium 0.0412
Calcium 0.0249
Potassium 0.0256
Bicarbonate 0.0164
For example, for a waste stream that has concentrations of 1,000 mg/l chloride and 1,000 mg/l sulfate,
the OP resulting from these constituents would be 1,000(0.0282) + 1,000(0.0104) = 38.6 mOsm/kg.
Aluminum Limits: Aluminum is evaluated using the water quality spreadsheet. Since aluminum is not
subject to an effluent limit guideline, the limits imposed in a permit are WQBELs. The values generated
by the water quality spreadsheet will be used as permit limits. However, when the result of the
spreadsheet is an instantaneous maximum limit greater than 10 mg/l, a monitor only requirement, rather
than a limit should be included in the permit. This is based on data collected from mine drainage
treatment facilities in Pennsylvania. This data shows that the treated effluents do not exceed 2.5 mg/l.
Stated another way, there is no reasonable potential for a mine drainage treatment facility to cause or
contribute to a violation of the aluminum water quality criteria, if the calculation from the spreadsheet
results in a value of 10 mg/l or greater.
General Procedures
The District Mining Office (DMO) will develop and issue NPDES permits for coal mining activities in a
manner consistent with state and federal regulations pertaining to technology-based and water quality-
based effluent requirements and other applicable requirements as outlined below.
Effluent limits are expressed as monthly average, daily maximum and/or instantaneous maximum.
40 CFR 122.45(d) requires that limits be stated as maximum daily and average monthly for continuous
discharges. Continuous discharges occur without interruption throughout the operating hours of a
facility. (40 CFR 122.2) In the mining context continuous discharges include, post-mining discharges
and pumped deep mine discharges. Stormwater induced discharges are not continuous discharges. For
mining discharges that are not continuous, effluent limits should be expressed as an instantaneous
maximum unless there is an applicable effluent limit guideline that is expressed as a monthly average or
daily maximum. Daily maximum and monthly average limits will be imposed as necessary to comply
with the effluent limitations at 25 Pa. Code §§ 87.102, 88.92, 88.187, 88.292, 89.52 and 90.102.
In the absence of another method to calculate limits, a useful reference is EPA‟s “Technical Support
Document for Water Quality-Based Toxics Control.” This method is useful when the water quality
criteria are expressed as a Criterion Maximum Concentration (CMC) or Criterion Chronic Concentration
(CCC) in 25 Pa. Code Chapter 16, Water Quality Toxics Management Strategy.
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This method includes the following steps:
1. Translate both the CCC and CMC to a long term average (LTA) to determine which is
controlling, using Table 5.1. Default to 0.6 coefficient of variation and use the 99th percentile.
2. Calculate the average monthly limit using Table 5.2. Default to 0.6 coefficient of variation, use
the 99th percentile and use a minimum n of 4.
3. Use the proportions (1:2:2.5) to determine the daily maximum and instantaneous maximum
limits.
Noncoal Mining and Mineral Processing Activities: The predominant types of non-coal mining/mineral
processing activities, and their associated NPDES technology-based effluent requirements, are shown in
Table C-1 in Appendix C. Also included in this table are additional technology-based requirements
which should be included in permits issued to such facilities.
The District Mine Office (DMO) will develop and issue NPDES permits based upon Table C-1. When
permitting non-coal mining where acid mine drainage problems may exist, metals parameters need to be
evaluated.
Underground Coal Mines, Coal Preparation Plants (Wet Processing), and Coal Refuse Disposal Sites:
Mine drainage and leachate discharges from these operations are generally fixed in terms of location,
quantity, quality and frequency of occurrence. As such, they can be considered similar to many other
types of industrial activity discharges. They also may occur at locations where they interact with other
industrial waste or sewage discharges. In order to calculate WQBELs for these mine drainage treatment
facilities the DMO will typically use the PentoxSD model or other mass balance tools and any
applicable TMDL report.
For bituminous deep mines, coal refuse disposal sites and preparation plants, the reasonable potential
analysis may include:
Use of PENTOXSD to calculate limits for treatment facilities
TDS/OP review for the aquatic life impact
TMDL review
TDS Review for PWS use (mass balance at the PWS intake)
Review for other pertinent parameters (e.g. chlorides, sulfates, toxics)
Water quality spreadsheet for stormwater controls
If the conclusion of the review is that there is no reasonable potential, then BAT limits apply.
If there is a reasonable potential, then WQBELs need to be applied.
Surface Coal Mining (including coal refuse reprocessing and stormwater related to underground
mines): Discharges from these activities are primarily precipitation-related and are less predictable in
terms of actual quantity, quality and frequency of occurrence. They are also relatively temporary when
compared with discharges from underground mines, prep plants and refuse disposal sites. DEP will
typically evaluate if WQBELs are needed for such activities using the WQSS described in Appendix B.
The procedure uses the watershed area (AW)/disturbed area (AD) ratio.
563-2112-115 / DRAFT December 27, 2014 / Page 11
Use of the WQSS enables DEP to make the following types of evaluations and decisions:
- Restricting the amount of acreage to be disturbed by a surface mining activity (i.e. as permit
condition)
- Restricting the extent of surface mining within a watershed area
- Establishment of stream monitoring networks within watersheds
- Evaluating/predicting in-stream impacts from multiple mining operations in a watershed
Special Protection Watersheds
DMO will implement DEP‟s policies and regulations for protection of special protection (HQ and EV)
waters when evaluating permits for mining activities. The process is described in the Anti-Degradation
Supplement for Mining Permits form (5600-PM-MR0007).
Post-Mining Discharges
For post-mining discharges, the review the water monitoring data of the receiving stream should inform
the decision as to whether WQBELs are needed. WQBELs for post-mining discharges should be
evaluated at the Q7-10 stream flow and the 95th percentile low flow. If the dataset for the 95th percentile
low flow is zero, then the lowest recorded flow should be used. The PENTOXSD model or a water
quality spreadsheet should be used to calculate the WQBELs. The WQBEL evaluation is particularly
important for manganese since the applicable effluent limit guidelines do not include manganese.
Q7-10 flow can be determined using methods described in USGS Water Resources Investigative
Report 99-4068 or the StreamStats tool.
Fact Sheet
A fact sheet is required for all draft NPDES permits. (Chapter 92a, § 92a.53) The effluent limits and
the methodology in determining the limits plus any specific permit conditions need to be documented on
the fact sheet.
Non-Discharge Alternatives
From a planning perspective, where more stringent effluent limits are required, non-discharge
alternatives should be considered. It may be more environmentally sound and cost-effective to
implement non-discharge techniques than to provide treatment that meets the required lower limits.
This is particularly true for cases where TDS and sulfate limits may be necessary due to a potential PWS
impact or where there is no available waste load allocation under a TMDL.
Stormwater General Permit for Mining
DEP has an NPDES General Permit (GP-104) for Stormwater for mine sites. This general permit
applies to earth disturbance activity of one acre or greater associated with mining.
563-2112-115 / DRAFT December 27, 2014 / Page 12
This general permit is issued in conjunction with a separate mining permit where the only potential
discharge to surface waters of the Commonwealth will be composed entirely of stormwater, in which the
main potential pollutant is sediment. Mining permit types to which the GP-104 is applicable include
coal and noncoal mining permits, small noncoal (and bluestone) permits, noncoal mining general
permits and exploration activities (in which case there is no mining permit).
The GP-104 cannot be used for sites that have an individual NPDES permit or another NPDES general
permit.
The general permit does not apply to those activities where one or more of the conditions listed in 25 Pa.
Code § 92a.54(e)(1)-(9) exist. For those situations or when otherwise notified by DEP, the operator
should file an application for an individual NPDES permit. An individual NPDES permit for a point
source discharge is necessary if the mining activity will or has the potential to discharge to High Quality
or Exceptional Value waters, including EV wetlands, or to streams listed as “impaired waters” for
sediment.
Compliance Schedules
In cases where the evaluation of effluent characterization data or permit review for a renewal or
modification requires the imposition of effluent limits for toxic pollutants or more stringent limits than
are already in the permit, a compliance schedule is appropriate to allow the applicant sufficient time to
meet the new limits. The regulations relating to NPDES permit compliance schedules are found at
25 Pa. Code § 92.5a.51.
A compliance schedule is appropriate when it is clear that it is not possible for the permittee to meet the
newly imposed limit(s) immediately. Compliance schedules need to establish the shortest reasonable
period of time to meet the new limits. For compliance schedules that exceed one year, annual
milestones are typically required. In many cases, time must be built into the schedule in order to
identify the appropriate treatment technology to be employed.
A compliance schedule should cover the following points:
1. A compliance schedule term, which could extend up to the full five-year term of the NPDES
permit. A longer term may be given under appropriate circumstances, however, a term longer
than five years may only be provided through entry of a consent decree by a court of competent
jurisdiction. The permittee should have the right to request approval of a modification of the
compliance schedule or any milestones therein conditioned upon the occurrence of events
beyond the control of the permittee.
2. Provisions for the permittee to develop and submit a report to DEP evaluating the treatment
technologies and identifying the preferred technology which will meet the effluent limitations in
the NPDES permit. The report may include specifications of the treatment equipment, proposed
schedule for construction and start-up, and demonstration that construction and start-up are to be
performed as soon as possible.
3. Provisions for the permittee to submit all necessary permits for the selected treatment equipment
after DEP approval of the treatment plan.
563-2112-115 / DRAFT December 27, 2014 / Page 13
4. Milestone dates (i) to begin and end construction of the treatment technology, (ii) to start-up the
“equipment,” and (iii) to demonstrate attainment with the applicable permit limits. These
milestone dates should consider DEP‟s issuance of any necessary construction permits.
5. Submission of periodic progress reports to DEP.
563-2
112-1
15 /
DR
AF
T D
ecem
ber
27, 2014 /
Pag
e 14
Ap
pen
dix
A
Min
ing E
fflu
ent
Ch
ara
cter
izati
on
Tab
le
T
ab
le I
I O
rga
nic
To
xic
s T
ab
le I
II O
ther
To
xic
s
Ta
ble
IV
Co
nv
enti
on
al
an
d
No
nco
nv
enti
on
al
Ta
ble
V T
oxic
an
d
Ha
zard
ou
s O
ther
Ite
ms
Tre
atm
ent
Fac
ilit
y
Ap
pli
cati
on
Req
uir
em
ents
-New
Per
mit
s
Rep
ort
tho
se e
xp
ecte
d t
o b
e
pre
sent-
incl
ud
e d
aily
max,
ave
and
so
urc
e
12
2.2
1(k
)(5
)(ii
i)(B
) S
BE
Ap
pli
es
Rep
ort
est
imat
es
of
tho
se e
xp
ecte
d t
o
be
pre
sent
12
2.2
1(k
)(5
)(ii
i)(A
)
Rep
ort
est
imat
es
of
tho
se e
xp
ecte
d t
o
be
pre
sent
and
tho
se l
imit
ed b
y a
n
EL
G
12
2.2
1(k
)(5
)(ii
)
Rep
ort
tho
se t
hat
are
exp
ecte
d t
o b
e
pre
sent.
D
ata
is n
ot
nee
ded
unle
ss i
t is
avai
lab
le
12
2.2
1(k
)(5
)(v)
Pro
vid
e d
ata
for
BO
D,
CO
D,
TO
C, T
SS
,
Am
mo
nia
N,
Tem
p (
win
ter
& s
um
mer
) an
d p
H
and
so
urc
e o
f d
ata.
[T
hes
e m
ay b
e w
aived
]
12
2.2
1(k
)(5
)(i)
Rep
ort
that
TC
DD
may b
e
dis
char
ged
if
2,4
,5-T
, 2
,4,5
-TP
, E
rbo
n, T
CH
or
HC
P a
re u
sed
or
mad
e 1
22
.21(k
)(5
)(iv
)
Tre
atm
ent
Fac
ilit
y
Ap
pli
cati
on
Req
uir
em
ents
-
Ren
ew
als
Ind
icat
e if
it
kno
ws
or
has
reas
on t
o b
elie
ve
these
wil
l
be
pre
sent-
dat
a is
req
uir
ed i
f
it i
s ex
pec
ted
that
the
conce
ntr
atio
n w
ill
be
gre
ater
than 1
0 p
pb
12
2.2
1(g
)(7
)(vi)
(B)
SB
E a
pp
lies
12
2.2
1(g
)(8
)
Co
al
- R
epo
rt d
ata.
12
2.2
1(g
)(7
)(v)(
B)
No
nco
al
- R
epo
rt
quan
tita
tive
dat
a
for
exp
ecte
d
po
lluta
nts
12
2.2
1(g
)(7
)(vi)
(B)
Pro
vid
e d
ata
for
EL
G l
imit
ed a
nd
dat
a o
r re
aso
n f
or
oth
ers
12
2.2
1(g
)(7
(vi)
(A)
Ind
icat
e w
hic
h o
nes
are
exp
ecte
d t
o b
e
pre
sent
and
rep
ort
any a
vai
lab
le d
ata
12
2.2
1(g
)(7
)(vii
)
Pro
vid
e d
ata
for
BO
D,
CO
D,
TO
C, T
SS
,
Am
mo
nia
N,
Tem
p (
win
ter
& s
um
mer
) an
d
pH
. [
Thes
e m
ay b
e w
aived
] 1
22
.21(g
)(7
)(ii
i)
Rep
ort
that
TC
DD
may b
e d
isch
arged
if
2,4
,5-
T, 2
,4,5
-TP
, E
rbo
n, T
CH
or
HC
P a
re u
sed
or
mad
e 1
22
.21
(g)(
7)(
vii
i)
Tre
atm
ent
Fac
ilit
y
Tw
o-y
ear
Sam
pli
ng
Req
uir
em
ent
Pro
vid
e d
ata
for
tho
se
exp
ecte
d t
o b
e p
rese
nt
12
2.2
1(k
)(5
)(vi)
SB
E A
pp
lies
Co
al
- S
ub
mit
dat
a
No
nco
al
- S
ub
mit
dat
a fo
r th
ose
exp
ecte
d t
o b
e
pre
sent
12
2.2
1(k
)(5
)(vi)
,
Fo
rm 2
C
Rep
ort
res
ult
s fo
r
tho
se e
xp
ecte
d t
o
be
pre
sent
12
2.2
1(k
)(5
)(vi)
,
Fo
rm 2
C
Anal
ysi
s no
t
req
uir
ed
SB
E A
pp
lies
F
orm
2C
No
t A
pp
lica
ble
sin
ce t
he
dat
a is
co
llec
ted
wit
h
the
app
lica
tio
n
Sto
rmw
ater
-New
Per
mit
s
Ap
pli
cati
on
Req
uir
em
ents
No
t R
equir
ed
12
2.2
6(c
)(1
)(i)
(G)
Pro
vid
e es
tim
ates
for
tho
se t
hat
are
kno
wn
or
bel
ieved
to b
e p
rese
nt
12
2.2
6(c
)(1
)(i)
(G)
Pro
vid
e es
tim
ates
for
tho
se t
hat
are
kno
wn
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ieved
pre
sent
12
2.2
6(c
)(1
)(i)
(G)
Anal
ysi
s no
t
req
uir
ed
Fo
rm 2
F
Pro
vid
e es
tim
ates
fo
r F
e, M
n;
Oil
& G
reas
e,
pH
, B
OD
5,
CO
D, T
SS
, P
, K
jeld
ahl
N,
Nit
rate
-
nit
rite
N,
Flo
w.
Als
o p
rovid
e fl
ow
est
imat
es.
12
2.2
6(c
)(1
)(i)
(G)
Sto
rmw
ater
-
Ren
ew
al
Ap
pli
cati
on
Req
uir
em
ents
Ind
icat
e if
it
kno
ws/
has
reas
on t
o b
elie
ve
these
wil
l
be
pre
sent
and
pro
vid
e d
ata
for
tho
se e
xp
ecte
d
12
2.2
1(g
)(7
)(vi)
(B)
SB
E A
pp
lies
Fo
rm 2
F
Pro
vid
e d
ata
for
tho
se t
hat
are
kno
wn
or
bel
ieved
to b
e p
rese
nt
12
2.2
6(c
)(1
)(i)
(E)
Pro
vid
e d
ata
for
tho
se t
hat
are
kno
wn
or
bel
ieved
to b
e p
rese
nt
12
2.2
6(c
)(1
)(i)
(E)
Anal
ysi
s no
t
req
uir
ed
Fo
rm 2
F
Pro
vid
e d
ata
for
Fe,
Mn,
and
oth
er p
oll
uta
nts
wit
h l
imit
s in
the
per
mit
; O
il &
Gre
ase,
pH
,
BO
D5
, C
OD
, T
SS
, P
, K
jeld
ahl
N,
Nit
rate
-
nit
rite
N,
Flo
w.
Als
o p
rovid
e d
ate/
dura
tio
n o
f
even
t sa
mp
led
. 1
22
.26(c
)(1)(
i)(E
)
563-2
112-1
15 /
DR
AF
T D
ecem
ber
27, 2014 /
Pag
e 15
T
ab
le I
I O
rga
nic
To
xic
s T
ab
le I
II O
ther
To
xic
s
Ta
ble
IV
Co
nv
enti
on
al
an
d
No
nco
nv
enti
on
al
Ta
ble
V T
oxic
an
d
Ha
zard
ou
s O
ther
Ite
ms
Sto
rmw
ater
Tw
o-
yea
r S
am
pli
ng
Pro
vid
e d
ata
for
tho
se t
hat
are
kno
wn o
r ex
pec
ted
to
be
pre
sent
12
2.2
6(c
)(1)(
i)(G
)
SB
E A
pp
lies
Fo
rm 2
F
Pro
vid
e d
ata
for
tho
se t
hat
are
kno
wn
or
bel
ieved
to b
e p
rese
nt
12
2.2
6(c
)(1
)(i)
(G)
Dat
a fo
r th
ose
kno
wn
or
bel
ieved
pre
sent
12
2.2
6(c
)(1
)(i)
(G)
Anal
ysi
s no
t
req
uir
ed
Fo
rm 2
F
Pro
vid
e d
ata
for
Fe,
Mn,
and
oth
er p
oll
uta
nts
wit
h l
imit
s in
the
per
mit
; O
il &
Gre
ase,
pH
,
BO
D5
, C
OD
, T
SS
, P
, K
jeld
ahl
N,
Nit
rate
-
nit
rite
N,
Flo
w.
Als
o p
rovid
e d
ate/
dura
tio
n o
f
even
t sa
mp
led
. 1
22
.26(c
)(1)(
i)(E
)
563-2112-115 / DRAFT December 27, 2014 / Page 16
Appendix B
Water Quality-Based Effluent Limit Calculations For
Coal Surface Mining Activities
Background
Development of WQ based effluent limit using conventional mass-balance WQ modeling techniques
requires fairly precise knowledge of wastewater discharge rate and low-flow rate of the receiving stream
along with several other variables described below:
QS = Flow rate of the receiving stream
CS = Upstream background concentration
QD = Wastewater discharge rate
CD = Concentration of pollutant in the wastewater discharge
QT = Resulting downstream flow rate (QS + QD)
CT = Resulting downstream pollutant concentration
The mass-balance equation is then established as follows:
QT CT =QS CS + QD CD (1)
and CD =[QT CT - QS CS] / QD (1.a)
where CD becomes the effluent limit required.
563-2112-115 / DRAFT December 27, 2014 / Page 17
In contrast to other types of mining activities, discharges from surface mining operations are less
predictable in terms of quantity, quality, frequency and pattern of occurrence. Such discharges
are primarily precipitation-related and generally exhibit some correlation with nearby stream
flows (i.e. discharge rates are higher when stream flows are higher and vice-versa).
Since QT = QS + QD, equation (1) can be rewritten as:
(QS + QD) CT = QS CS + QD CD
QS CT + QD CT = QS CS + QD CD
QS (CT - CS) = QD (CD - CT)
and
QD / QS =( CT - CS) / (CD - CT) (2)
For a watershed impacted by surface mining and for a given precipitation pattern, it can
generally be assumed that:
QS is proportional to the watershed area (AW) for the stream segment impacted by mining
QD is proportional to the disturbed area associated with mining (AD)
Equation (2) can then be rewritten as:
AD / AW = (CT - CS ) / (CD - CT) (3)
Equation (3) can be used to determine the ratio of AD/AW which is necessary to protect
downstream water quality for a pollutant of concern by further assuming that:
CD = the BAT effluent level for the pollutant (average monthly)
CT = instream Ch. 93 WQ criterion value for the pollutant
CS = upstream background level of the pollutant
Alternatively, Equation (3) can be further modified to determine the allowable WQ based
discharge concentration (CD ) for a given drainage ratio AD /Aw, as follows:
CD = [(CT - CS) / (AD / AW)] + CT (4)
Spreadsheet for WQ-Based Effluent Limit Calculations
DEP has developed a water quality Excel spreadsheet (WQSS), which incorporates the principles
described in Equations (3) and (4).
Figure 1 shows a generic surface mine permit area within a watershed drainage area, with a receiving
stream. During the life of the surface mine there will be several discharges from sediment control ponds
and from a mine drainage treatment pond. The exact location of these discharges may change as mining
proceeds. The focus of the WQSS analysis is to determine if effluent limits stricter than the Group A
limits in Table C-2 should be assigned to the mine drainage discharge to protect in-stream water quality.
A conservative approach, described below, is followed when determining the ratio of watershed
drainage area (Aw) “disturbed area” to (AD).
563-2112-115 / DRAFT December 27, 2014 / Page 18
The value of AD is developed by first determining the maximum area disturbed (i.e. not revegetated to
Stage II Bond Release Standards) during the life of the mine site. The maximum area of open pit plus
unregraded spoil piles is multiplied by a factor of at least 2.0. This pit/spoil multiplier can be increased,
however, to reflect additional drainage due to groundwater entering the pit (see Table 1).
The value of Aw is developed by first determining the watershed area above the point of evaluation
(Point A in Figure 1) and then it is adjusted by subtracting the maximum area disturbed (including
pit/spoil area).
The “available dilution” is then calculated using the formula:
For “high quality” streams, the WQSS incorporates a minimum Aw/AD ratio of 6:1.
563-2112-115 / DRAFT December 27, 2014 / Page 19
Figure 1. - Hypothetical
Watershed and Surface Mine Permit (SMP)
Configuration
563-2112-115 / DRAFT December 27, 2014 / Page 20
Table 1. - Discharge Multiplier Values for Pit and Unregraded Spoil Area
Discharge
Multiplier
Site Conditions
2 Mine site located on hilltop, above regional water table. Few or
no springs or seeps located in area to be mined. Little
groundwater flow into expected.
4 Mine site probably below regional or significant perched water
table. Some groundwater flow into pit expected. Springs or
seeps present within stratigraphic interval to be mined.
6 or greater depending on
conditions
Mine site located below regional water table in a significant
groundwater discharge zone, i.e. pit below major stream level or
abundant indications of groundwater discharge present.
The spreadsheet uses equations (3) and (4) to calculate the required minimum dilution ratio to meet
in-stream criteria and, alternately, the required wastewater effluent limit to meet in-stream criteria (using
the available dilution without any flow controls). Where it is difficult to control the discharge rate, or
where flow measurements of the receiving stream and discharges are impractical, the permit contains
WQ-based effluent limits rather than BAT limits with a WQ-based dilution ratio requirement.
563-2112-115 / DRAFT December 27, 2014 / Page 21
Appendix C
Table C-1. Summary of EPA’s Technology-Based NPDES Effluent Requirements For Non-Coal
Mineral Mining and Processing (40 CFR 436)
Type of Non-Coal
Mining Activity
40 CFR
436
Subpart
Technology-Based Requirements Additional PA
Requirements
(See Note 1) 30 Day Avg 1-Day Max
Crushed Stone
(Limestone quarries and
crushing/sizing operations)
B pH* 6-9 at all times 6-9 at all times TSS 35/70 mg/l
Use of std. E&SC
practices and BMP
controls
Construction Sand and
Gravel
(aggregate for general
construction purposes, or
materials to be used as fill)
C pH* 6-9 at all times 6-9 at all times TSS 35/70 mg/l
Use of std. E&SC
practices and BMP
controls.
Industrial Sand
(Non-construction uses
such as refractories,
abrasives, glass making)
D TSS*
pH*
25 mg/l
45 mg/l
6-9 at all times
Use of std. E&SC
practices and BMP
controls
1 Additional effluent limits, E&SC practices, and BMP controls to be evaluated on a case-by-case basis,
considering the type(s) of discharges present and additional WQ protection needs.
Limit does not apply for discharges resulting from >, 10-yr., 24-hr. precipitation event.
563-2112-115 / DRAFT December 27, 2014 / Page 22
Table C-2. Summary of Technology-Based Effluent Requirements For Coal Mining Activities*
Part 1 - Discharge Limitation Groupings
Group A 30-day
Average
Daily
maximum
Instantaneous
maximum
Iron (total) 3.0 mg/l 6.0 mg/l 7.0 mg/l
Manganese (total) 2.0 mg/l 4.0 mg/l 5.0 mg/l
Suspended Solids 35 mg/l 70 mg/l 90 mg/l
pH 6-9 at all times
Alkalinity >acidity at all times
Group B 30-day
Average
Daily
maximum
Instantaneous
maximum
Iron (total) 7.0 mg/l
Settleable Solids 0.5 ml/l
pH 6-9 at all times
Alkalinity >acidity at all times
Group C 30-day
Average
Daily
maximum
Instantaneous
maximum
pH 6-9 at all times
Alkalinity >acidity at all times
Part 2 - Discharge Situations and Applicable Discharge Limitation Groupings
Type Discharge Weather Conditions/Precipitation
Events
Effluent
Limitations
Pit Water from Surface Mines all Group A
Drainage from Underground
Mine Workings
all Group A
Drainage from coal refuse
disposal piles
dry weather, and less than or
equal to 1 yr-24 hr
greater than 1 yr-24 hr to
less than or equal to 10 yr-24 hr
greater than 10 yr-24 hr
Group A
Group B
Group C
Surface runoff from active
mining area and from area
where Stage II reclamation
standards achieved
dry weather
less than or equal to 10 yr-24 hr
greater than 10 yr-24 hr
Group A
Group B
Group C
All other discharges dry weather
less than or equal to 10 yr-24 hr
Greater than 10 yr-24 hr
Group A
Group B
Group C
*Pursuant to regulations 25 Pa. Code §§ 87.102, 88.92, 88.187, 88.292, 89.52 and 90.102.